depends on each SARM. YK-11 and S-23 are somewhat liver toxic, although unlikely to cause any liver damage even if you use them for 12 weeks. but it depends on the dosage and on each individual too.
Why would you change? 5 lbs during the first 4 weeks is great. consdering that 5 lbs of lean muscle mass is great enough. moreover, it also depends on your diet and workout plan, don't forget about it.
and because people give up to soon in my opinion. i've seen people giving up after 3-6 months because they were not experiencing the results they were hoping for. but let's admit it - that's not enough to get any mind blowing results.
@RedRid is right. If I use ostarine with stenabolic and cardarine I can safely run them for 12 weeks without any issues. If I use S23 with RAD, for example, I already feel the suppression at 8 week
obviously. those who just started to work out will notice awesome results in just one month. professionals will struggle to gain a single lb of muscle after years of training.